Railway signaling apparatus



Patented Oct. 9, 1928.

UNITED STATES PATENT oFF1cr...

ROBERT M. GILSON, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA.

RAILWAY SIGNALING APP ARATUS.

Application filed August 4, 1926. Serial No. 127,007.;

My invention relates to railway signaling apparatus and particularly to apparatus of the type involving track circuits.

I will describe three forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a diagrammatic view showing a modi tied form of apparatus embodying my invention and suitable for use in connection with two track circuits the track relays of which are located adjacent the point ofjunction of the two circuits. Fig. 3 is a diagrammatic view showing a further modification of my invention suitable for use in connection with two parallel tracks.

Similar similar parts in each of the views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the rails of a railway track, which rails are divided by reference characters refer to insulated joints 2 to form a section EF. This section is provided wlth a track c1rcuit comprising a transformer T having its secondary connected across the rails through a limiting'reactance 29, and a track relay E having two windings 6 and 7, the former of which is connected across the rails of the section. The primary of the transformer T is constantly energized from a source ofalternating current not shown in the drawing. The second winding 7 of track relay R is also supplied with alternating current from the secondary of a transformer L, the primary of which is constantly energized from a suitable, source of alternating current. Inter-posed between the secondary of transformer L and the winding 7 is a primary 5 of a transformer C, the Second-* ary 4; of which is connected with the mid point of a reactance A and with an auxiliary conductor B. The reactance A is connected across the track rails l and l of the section E-F, and the auxiliary conductor B is in Contact with the track ballast. ductor B is preferably located midway be tween the rails l and 1 and may, for example, be spiked to the usual ties which support these rails. u

As is well understood in the railway signaling art, the ballast leakage resistance of a This contrack section, that is, the resistance from rail to ra l through ties and ballast, varies through wide limits depending upon weather conditions. When the ballast is wet, this' voltage applied to winding 6 of relay R will therefore vary in accordance with the condition of the ballast, and in the absence of any preventive means the torque exerted by this relay will vary correspondingly.

Considering the transformer C, when the ballast resistance is high, the secondary 4 i i of this transformer is practically on open circuit, so that thecurrent in the local windmg? of relay R is reduced to a amount equal to the magnetizing current .of the transformerC. Whenthe resistan'ceof the ballast is extremely low, the, secondary 4 of transformer C is practically on short circuit, so that the full voltage of transformer L is applied to winding 7. The increased current in the local winding 7 of relayv R will compensate forthe reduced amount of current ingthe track winding 6 due to wet ballast conditions, and so it'will be seen that practically a constant torque may he obtained in the track relay under all weather conditions. This permits high energization of the track circuittotake care of wet weather conditions without impairing the shunting sensitivity of the track circuit under dry weather conditions. a

Referring now to Fig. 2, vI have here shown two adjoining track sections EF -andjFG, which track sections are provided secondary of transformer L throughthe' primary 5 of transformer C. Theterminals of secondary 4 of transformer C are connected respectively with two conductors B and E the former of which is in contact with the ballast in section EF and the latter of which is in contact with the ballast of section F G. The ratio of turns in the windings of transformer C are such as to obtain the same characteristics with the two relay windings 7 in circuit with this transformer as those obtained in Fig. 1 with but one relay winding connected with this transformer.

Referring now to Fig. 3, I have here shown two parallel railway tracks X and Y, each of which is divided into sections E-F and F-G. Section E-F of track X is provided with a track circuit which is the same as that shown in Fig. 1, and section FG of track Y is provided with a similar track circuit. In this View the windings 7 of the two track relays Iiiand R are energized in multiple from transformer L through primary winding of transformer C, and the terminals of secondary at of the latter transformer are, connected respectively with a reactance A and a reactance A Iteactance A is connected across the rails of section EF of track X, whereas reactance A is connected across the rails of section F-G of track Y. The characteristics. and operation of the apparatus shown in Fig. 3 are the same as those of the apparatus shown in Figs. 1 and 2. That is, under dry weather conditions the secondary l: of transformer C will be practically on open circuit, and under wet weather conditions this secondary will be practically on short circuit because of the low resistance of the ballast and ground between reactances A and A The primary 5 of transformer C will vary the amount of current supplied to the local windings 7 accordingly. v

Referring now to all of the views, if the track relays are of the polyphase type requiring currents disposed in quadrature relation in their two windings for best operation, they will be protected against false olperation due to any unbalance in the piantom leakage current, because of phantom leakage current which flows through the track element of the relay will be nearly in phase with the current in the local winding? and wvill, therefore, produce practically no torque in the relay.

Although I have herein shown and dei scribed only three forms of'apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1, In a signal system involving a section of railway track, a source of track circuit voltage connected with the rails of said section and a track relay having a first winding receiving energy from said rails and a second winding supplied with Voltage, the com bination with the aforementioned.instrumein talities of an auxiliary conductor in contact with the track ballast, and a transformer having its primary included in circuit with said second winding and the terminals of its secondary connected with said conductor and the track rails.

2. In a signal system involving a section of railway track, a source of track circuit voltage connected with the rails of said section and a track relay having a first winding receiving energy from said rails and a second windin sun lied with VOlta B the combination with the aforementioned instrumentalities of an auxiliary conductor in contact with the'track ballast, an impedance connected across the rails of said section, and a transformer having its primary included in circuit with said secondwinding and the terminals of its secondary connected with said conductor and an intermediate point in said impedance.

, 3. In a signal system involving a section of railway track, a source of track circuit voltage connected with the rails of said sec tion, and a track relay having a first windingreceiving energy from said rails and a second winding supplied with voltage, the combination with the aforementioned instrumentalities of a coil in series with said second winding, and means responsive to variations in the resistance of the track ballast for varying the effective reactance of said coil.

i. In a signal system involving a section of railway track, a source of track circuit voltage connected with the rails of said section, and a track relay having a first winding receiving energy from said rails and a second winding supplied with voltage, the combination with the aforementioned instrumentalities of an auxiliary conductor in.

contact with the track ballast, a coil in series with said second winding, and means responsive to variations in the resistance of the track ballast between said auxiliary conductor and the track rails for varying theeffective reactance of said coil.

5. In combination with a section of rail way track provided with a source of track circuit voltage and a track relay, an auxiliary conductor in contact with the track ballast, and a transformer havingits primary included in circuit with a winding of said relay and its secondary terminals connected with said conductor and the track rails.

6. In combination with a section of railway track provided with a source of track circuit voltage and a track relay, an auxiliary conductor in contact with the track ballast, an impedance connected across the rails of said section, and a transformer having its primary included in circuit with a winding of said relay and the terminals of its secondary connected with said conductor and with an intermediate point in said impedance.

7 .In combination with a section of rail way track provided with a source of track circuit voltage and a track relay, an auxiliary conductor in contact with the track bal- 1 last, a coil in series with a Winding of said rails for varying the effective reactance of said c0il.

In testlmony whereof I aflix my signature.

ROBERT M. GIL'SON. 

